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>>> >>>     asm volatile (".byte 0xf2, 0x0f, 0x01, 0xfc" >>>                  : "=ccc" (res) >>>                  : "a" (addr), "c" (fn)); >>> >>>     return res; >>> } >>> >> The above constraints to use on_each_cpu_mask() is forcing the use of: >> >> void rmpopt(void *val) > > No.  You don't break your thin wrapper in order to force it into a > wrong-shaped hole. > > You need something like this: > > void do_rmpopt_optimise(void *val) > { >     unsigned long addr = *(unsigned long *)val; > >     WARN_ON_ONCE(__rmpopt(addr, OPTIMISE)); > } > > to invoke the wrapper safely from the IPI.  That will at obvious when > something wrong occurs. This wrapper i can/will use, but doing a WARN_ON_ONCE() is probably avoidable as there will be ranges where RMPOPT will always fail, such as while checking the RMP table entries itself, so there is a good chance that we will always trigger the WARN_ON_ONCE() on the memory range containing the RMP table. Thanks, Ashish > > ~Andrew